Many commercial hair styling products in form of sprays, lotions, gels, and mousses, use resins or gums to provide long term hold of up to several hours. However, gums and resins in hair styling products make the hair sticky and stiff, with an unnatural appearance, and are difficult to wash out. In search of a balance between hold and flexibility, some have turned to thermoplastic elastomeric copolymers, which provide measures of hold and flexibility, with a more natural appearance. In general, however, thermoplastic elastomeric copolymers are difficult to incorporate into shampoo and conditioner products, due to their low solubility into water and alcohol. To address the low solubility issue specific copolymer systems have been proposed.
U.S. Pat. Nos. 6,537,532 and 5,916,547 (Torgerson, et. al.) disclose triblock copolymer systems, ABC. The ‘A’ block is a thermoplastic elastomer that softens upon heating, but exhibits resistance to deformation at room temperature and below. The ‘A’ block acts as a backbone of the subject copolymers, and is made of polymerizable, ethylenically unsaturated monomer, such as acrylic acid, salts, esters and amides thereof. A ‘B’ block is a hydrophilic macromonomer unit of polyethylene glycol-type polymer. ‘B’ units are arranged as side chains on the ‘A’ backbone. As thermoplastic elastomers typically have low water solubility, the presence of the ‘B’ block side chains has the benefit of increasing the water solubility of the copolymer system. The ‘C’ block units are polysiloxane macromonomers, also arranged as side chains on the ‘A’ backbone. It is reported that the triblock copolymer systems display at least two distinct glass transition temperatures, one for the backbone and polysiloxane side chains, (about −130° C. to −10° C.), and one for the hydrophilic side chains (greater than room temperature, i.e. >20-25° C.). Because the copolymers are typically used at temperatures above the glass transition temperature of the backbone and polysiloxane side chains, the copolymers maintain a degree of flexibility. On the other hand, at room temperature, which is below the glass transition temperature of the hydrophilic side chains, the copolymers will have a degree of structural rigidity from these hydrophilic side chains. The copolymers are said to be water and alcohol soluble or dispersible, and are appropriate for use in hair care applications, where a strong, yet flexible hold for style retention is desired, along with a smooth feel and shine.
U.S. Pat. No. 5,730,966 (Torgerson, et. al) discloses water or alcohol soluble thermoplastic elastomeric copolymers having two or more polymeric pendant side chains. The copolymer is formed from the copolymerization of randomly repeating A and B units, where ‘A’ is a monomer and ‘B’ is a hydrophilic macromonomer. The copolymer has an average molecular weight greater than 10,000 Daltons, and has two distinct glass transition temperatures; one less than 0° C. and one greater than 25° C. The copolymers are incorporated into hair and/or skin care applications.
U.S. Pat. No. 6,165,455 (Torgerson, et. al) discloses hair care compositions containing nonpolar graft thermoplastic elastomeric copolymers and a water insoluble volatile solvent for the copolymers. In this case a thermoplastic elastomeric backbone is grafted with hydrophobic and polysiloxane macromonomers to form an ABC copolymer.
U.S. Pat. No. 6,074,628 (Bolich, Jr., et. al) discloses hairspray compositions with an alcohol solvent and a silicone-containing adhesive block copolymer. The block copolymers are either A-B, A-B-A or -(A-B)n- type structures. It is reported that the alcohol solvents, combined with the select silicone-containing adhesive block polymers were effective at providing improved hair styling performance, specifically minimizing or eliminating the undesirable drooping of dry, styled or positioned hair.
These and other hair styling compositions rely on a silicone grafted block copolymers that are relatively hard to make and/or expensive to purchase. None of the foregoing references discloses two specific types of acrylate silicone copolymers mixed in the well defined ratios disclosed herein. The present invention identifies well defined mixtures of two specific types of acrylate silicone copolymers for use in easy-to-formulate hair care products. The acrylate silicone copolymers are water dispersible. The aqueous shampoos and conditioners that comprise these two copolymers as their exclusive or main hair styling ingredients offer hair styling and hold benefits that are at least as good as commercially available hair styling products, albeit with a more natural appearance. These benefits are achievable even when the product is implemented as a rinse-out product.
Objectives
The main objective of the present invention is a water-based hair styling composition that is easy to make, and that provides excellent flexibility and hold with a natural (i.e. not overly stiff) appearance.
Another objective is to provide a flexible polymer system that, when incorporated into a rinse-our product (i.e. a shampoo or conditioner), offers flexibility and hold that are comparable to leave-in hair styling products with gums and resins.